In the semiconductor manufacture process, a plasma processing apparatus is widely used in the fine processing processes such as film deposition, etching, and ashing. The process by plasma processing performs a prescribed process in the following manner. A process gas introduced into a vacuum chamber (reactor) is transformed into a plasma by plasma generation means. The resulting plasma is allowed to react on the semiconductor wafer surface to perform a fine processing, and volatile reaction products are discharged.
The present invention covers the apparatus utilizing a plasma in general. Now, the prior art will be explained by taking as an example an apparatus called an ECR (Electron Cyclotron Resonance) system which is one of those apparatuses. This ECR system generates a plasma by microwave discharge in a vacuum chamber externally applied with a magnetic field. In order to accelerate ions incident on a sample, a bias voltage is applied to the sample.
The device configuration of a semiconductor element has become increasingly complicated in recent years, so that there are demands for an increase in speed of processing and a reduction in number of steps in the manufacturing process thereof. Namely, for a semiconductor integrated device, with a request for downsizing, for example, for a pitch between wirings of about 0.2 μm or less, the capacitance between neighboring wirings relatively increases at the wiring portion. If a conventional silicon dioxide film is used as an insulating material between wirings of such a device, it becomes impossible to enjoy benefits due to higher speed of a transistor resulting from downsizing. For this reason, a material with a low dielectric constant (k value) such as SiOC is employed as an interwiring insulating material.
The material with a low dielectric constant (k value) is mainly used in combination with copper as a wiring material, and formed by a process called dual damascene. This requires a step of etching processing of an insulating film. The dual damascene formation process includes a step of processing and transferring a trench profile into a porous insulating film using a hard mask, and imparting a prescribed profile to a sample having a hole profile processed in the previous step. Such a technology is disclosed, for example, in Japanese Patent Laid-open No. H 9(1997)-115878.
Further, a method for monitoring the processing state, and controlling the process is also adopted in the prior art. As the method for monitoring the processing state, and controlling the process, for example, there is known the method in which a reflected interference light from a processed wafer is monitored to terminate etching processing, disclosed in U.S. Pat. No. 5,658,418.
Still further, in the prior art, removal of the mask material is carried out by means of another vacuum chamber or device in the same apparatus after the completion of etching. For example, Japanese Patent Laid-open No. 2000-352827 discloses a technology for removing the etching residues and the resist surface cured layer by a wet processing.
In the prior art, removal of the mask material is carried out by means of another vacuum chamber or device in the same apparatus after the completion of etching. This results in an increase in number of steps, and accordingly, a reduction in total throughput, and requires another vacuum chamber (device).
Further, with a method for carrying out the removal of the mask material by only an oxygen plasma, it is difficult to remove a silicon component remaining on the surface, and the mask material including a cured mask layer. Now, a consideration will be given to the case where a prescribed pattern such as a trench 121 is formed to the position indicated by a dotted line in the resist formed on an insulating film 120 made of SiOC as the surface processing of a wafer as shown in FIG. 4. On the surface of the mask material after etching, there remains an area including a cured layer 124 of a resist resulting from heat input from a plasma. In the cured layer 124, Si in the insulating film 120 separated by etching is also deposited. With the method for carrying out the removal of the mask material only by an oxygen plasma, it is impossible to remove such a cured mask layer in the surface of the mask material. Further, a damaged portion 125 in the film layer also occurs.